The invention disclosed herein pertains to an endoscope used to visualize the urinary system. As shown in FIG. 1, kidneys 13 of the human body are connected to a bladder 9 by very narrow ducts called ureters 11. The openings of the ureters 11 into urinary bladder 9 are about 1 to 4 mm wide. Bladder 9 is partially surrounded from behind by pelvis 15 which serves as a protective shield for the bladder. The natural flow of body fluids is from the kidneys 13 through ureters 11 into bladder area 9 and is discharged from the body through urethra 17. The opening of the urethra to release fluids from the body is about 5 mm to 10 mm wide.
Urinary bladder stones 8 and kidney stones 7 have been known to become lodged in the bladder 9 and ureters 11, as well as in the calyxes 5 of the kidney 13, respectively. This causes blockage of flowing body fluids and is very painful. Various medical devices have been developed to remove bladder stones 8, and/or kidney stones 7. The devices for removing these stones are pertinent to the general subject matter of the present invention.
The medical devices which have been developed to remove kidney stones generally involve a device called a ureteroscope. The ureteroscope is positioned within the body (i.e. urethra 17, bladder 9 and ureter 11) and has working channels which provide access to and from the areas where stones 7, 8 are lodged. A typical ureteroscope is rigid along its length so as to enable axial and rotational translation in the bladder 9 areas. Typically, the rigid ureteroscope is greater than 3 mm in diameter and therefore unable to fit through most openings into ureters 11 in their natural size. Ureters 11 can be mechanically dilated by separate accessory means to accommodate the ureteroscope. This dilation, however, is traumatic to the body. Even after entering the ureter 11, and subsequently the kidneys 13, the rigid ureteroscope is unable to bend toward kidney stones 7 lodged in calyxes 5 of kidneys 13.
Flexible ureteroscopes have been developed to serve the same purpose as the rigid ureteroscopes. Typically, these ureteroscopes tend to be too flexible to allow adequate control when adjusted from a handle at a proximal end. Proper manual control requires a more rigid length for the endoscope to be effectively moved along the urinary tract.
A rigid endoscope with a flexible tip is disclosed in U.S. Pat. Application Ser. No. 089,579, assigned to the assignee of the present invention. The rigid length of the endoscope has an outer diameter of 3 mm or less, and includes a flexible tip portion at the distal end which is controllable from the endoscope handle. The flexible tip portion is designed to fit easily into a desired ureter, and thereafter bend toward kidney stones 7 in calyxes 5.
Employed within a working channel of a ureteroscope are various mechanical accessories for engulfing and retrieving, or grasping and crushing kidney stones 7. Also, a rigid ultrasound probe for delivering ultrasound waves to break the kidney stones 7 has been developed to be employed in a working channel of a rigid ureteroscope. Further, an electrohydraulic generator has been developed to generate a spark at the tip of a probe to break target kidney stones 7 which are located with the ureteroscope.
Recently, "extracorporeal acoustic shock wave" therapy has been used to break kidney stones into particles which are small enough to pass through the ureter and urethra by natural means. This therapy involves immersing the patient in a bath of water or placing the body of the patient in contact with a water column enclosing a shock wave generator. Shock waves are generated in the water and focused toward the areas where target kidney stones are lodged. The waves penetrate the body from the outside and break the target stones. However, such acoustic shock wave therapy or treatment may not affect kidney stones which are lodged in the lower region of ureters 11 and protected by the surrounding pelvis 15.
More recently, the Candela Laser Corporation, Wayland, Mass., has developed a dye laser to apply a photoacoustic effect to kidney stones 7 which are lodged in areas protected by the pelvis 15 and in other areas. Such an effect breaks the stones into particles which are small enough to pass through the ureter and urethra.